DESCRIPTION (provided by applicant This application is in response to "PAR-09-118 - Recovery Act Limited Competition: High-End Instrumentation Grant Program (S10)" With this application we request funding for the acquisition of a frequency-domain diffusive optical imaging (DOT) system for the Biomedical Imaging Center at the University of Illinois. DOT is an emerging technology that enables the non- invasive measurement of a number of physiological parameters of the brain with a combination of temporal (<50 ms) and spatial (<1 cm) resolution (when high-density recording and mapping techniques are used). Specifically, funds are requested for the acquisition of a 128-source, 24-detector Dual-Imagent system produced by ISS Inc., located in Champaign, Illinois, capable of recording up to 1,536 channels (source-detector combinations). The system will come equipped with 10 meter-long, non-magnetic fibers that will allow its use both inside and outside the 3T full-body Siemens TRIO magnetic resonance (MR) scanner that will be installed at the Biomedical Imaging Center (BIC) in July, 2009. Among the physiological variables that can be assessed using the Dual-Imagent are the relative and absolute concentration of oxy- and deoxy-hemoglobin, as well as total hemoglobin and saturation level in brain tissue, pulse parameters associated with arterial elasticity and stiffness, and scattering changes associated with neuronal activity (fast optical signal, FOS, and the event-related optical signal, EROS). In addition, the system bundle will also include an optical 3-D digitizing device for accurate co-registration of the functional optical data with structural MR images. Our group, and in particular the principal investigator, has extensive experience with the use of optical instruments, and has played a critical role in the development of fast optical signals. If the project is funded, BIC will hire an experienced scientist (Dr. Maclin) at 50 percent to provide support for users of the machine. The acquisition of the new system will allow a large number of investigators, most of whom are recipient of R01 NIH funding, to perform optical research, which will greatly enhance their research programs. A list of major and minor users, and descriptions of the way in which they will use the new optical system, are provided with this application.